This invention relates to latently curable one-part epoxy resin compositions.
Epoxy resins, i.e., organic compounds having one or more terminal or pendant oxirane groups, ##STR1## have been widely used for many years in adhesive compositions. Various curatives, accelerators, and additives have been used with the epoxy resins to modify the curing properties and adhesive characteristics.
U.S. Pat. No. 3,553,166 (Anderson et al.) and U.S. Pat. No. 3,677,978 (Dowbenko et al.) disclose storage stable, elevated temperature curable epoxy resin compositions which contain epoxy resin and, as a curing agent, a metal salt complex of an imidazole. Anderson further discloses the addition of nitrogenous compounds to improve structural strength.
Other various curing systems disclosed for use with epoxy resins include dialky/amino-alkylimidazoles in U.S. Pat. No. 3,912,689 (Bechara et al.) fluoroalkylsulfonate salts of a metal coordinated with imidazole or substituted imidazole ligands in U.S. Pat. No. 4,101,514 (Thom), phthalic acid derivatives which are substituted by alkenylamino groups in U.S. Pat. No. 4,140,703, imidyl-and isoimidyl-phthalic anhydrides in U.S. Pat. No. 4,160,081 (Kvita et al.), imidyl-benzene-dicarboxylic and -tricarboxylic acid derivatives in U.S. Pat. No. 4,233,220 (Kvita et al.), imidazole accelerators with aromatic polyol hardeners in U.S. Pat. No. 4,246,162 (Schreiber), isocyanate blocked imidazoles and imidazolines in U.S. Pat. No. 4,355,228 (Beitchman et al.), naphthyl diisocyanate blocked imidazole in U.S. Pat. No. 4,533,715 (Lee et al.), solutions or eutectic mixtures of imidazoles with N,N'-dihydroxyethyl-5-,5-dimethyl hydantoin or trimethylpentanediol in U.S. Pat. No. 4,417,010 (Shimp) and a liquid blend of an imidazole and a mixture of trimethylolpropane and 1,4-butanediol in European Patent Application No. 0 118,270 (Celanese).